Photodetectors are devices that sense the presence of light or other electromagnetic energy. A PIN diode is one example of a photodetector. The PIN diode detects the presence of an optical signal when the optical signal contacts the intrinsic region of the diode freeing an electron or hole. An external power source applies voltage to P-type and N-type regions of the diode causing the freed electrons or holes to be swept from the intrinsic region producing a current. This electrical current indicates the presence of light or other electromagnetic energy entering the detector.
Typically, photodetectors are designed to absorb the optical signal inducing an electron, or hole to be released from the intrinsic region. Such a design results in the optical signal terminating upon contact with the intrinsic region of the photodetector. As advances in technology focus on reducing the size of electronic devices, integrated circuits need to be designed with consideration towards the interface between various circuit components. Improvements are always desired in any art.